[Accessor] Set default dimension to 1

Done for device, host, and local accessors.
Not done for image accessors because there might be some inconsistency
between sampled and unsampled image accessors.

Author: ProGTX

adoc/headers/accessorBuffer.h

@@ -25,7 +25,7 @@ enum class placeholder { // Deprecated
 
 
 template <typename dataT,
-          int dimensions,
+          int dimensions = 1,
           access_mode accessMode =
             (std::is_const_v<dataT> ? access_mode::read
                                     : access_mode::read_write),

adoc/headers/accessorHost.h

@@ -3,7 +3,7 @@
 
 namespace sycl {
 template <typename dataT,
-          int dimensions,
+          int dimensions = 1,
           access_mode accessMode =
             (std::is_const_v<dataT> ? access_mode::read
                                     : access_mode::read_write),

adoc/headers/accessorLocal.h

@@ -2,7 +2,7 @@
 // SPDX-License-Identifier: Apache-2.0
 
 namespace sycl {
-template <typename dataT, int dimensions>
+template <typename dataT, int dimensions = 1>
 class local_accessor {
  public:
   using value_type =             // const dataT for read-only accessors, dataT otherwise